1. Preheat the oven to slow (150C/130C fan forced). Grease two oven trays and line with baking paper.
2. Beat egg whites in a small bowl with an electric mixer until soft peaks form. Add sugar and food colouring, beat until sugar dissolves. Transfer mixture to a large bowl. Fold in essence if using, sifted icing sugar and almond meal in two batches.
3. Spoon Mixture into a large piping bag fitted with 1.5cm plain tube. Pipe 4cm rounds, 2cm apart, onto prepared trays. Tap trays on bench to allow macaroons to spread slightly. Flatten peaks lightly with a damp finger. Dust with extra icing sugar. Stand for fifteen minutes.
4. Bake macaroons in a slow oven for about 20 minutes or until dry to touch. Stand macaroons on trays for five minutes. Transfer onto a wire rack to cool.
5. White Chocolate Ganache: Meanwhile, combine chocolate and cream in a small heatproof bowl over a pan of simmering water; stir until the chocolate is melted. Tint with a few drops of food colouring. Cover; refrigerate until mixture is a spreadable consistency.
6. Sandwich macaroons together with white chocolate ganache.